The present invention relates to a battery operated information processing apparatus such as portable terminal equipment, lap-top personal computers and the like, now used widely.
For purposes of miniaturization, such a conventional battery driven information processing apparatus has only a single CPU which is used for executing all necessary processes such as executing an application program, processing an input from a keyboard, processing communications, and processing interruptions.
Even in an information processing apparatus having a sub-CPU for handling keyboard operations, communications and the like, the sub-CPU is controlled by the main CPU at all times. Therefore, the main CPU which consumes a large power occupies a large part of the operating time of the apparatus.
In the conventional information processing apparatus, the main CPU consuming a large power always controls the entirety of the apparatus including a sub-CPU and other peripheral circuits, thus making it difficult to achieve low overall power consumption by the apparatus.